A 50-year-old man comes to the office for a routine physical. He has had no recent concerns and his review of systems is unremarkable. Five years ago, the patient underwent mechanical aortic valve replacement due to endocarditis. Since then, he has been taking warfarin for anticoagulation and has been compliant with the regimen. The patient is a lifelong nonsmoker. All his vaccinations are up to date. He is afebrile, blood pressure is 122/65 mm Hg, and pulse is 73/min and regular. On auscultation, a 2/4 diastolic murmur is heard at the left sternal border and is best appreciated with a breath-hold at expiration. The lungs are clear. Abdominal and extremity examinations are unremarkable. His last INR check 5 days ago was 2.9. Which of the following is the best next step in management of this patient?
Prosthetic valve dysfunction | |
Types & causes |
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Clinical manifestations |
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Diagnosis |
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IE = infective endocarditis. | |
This patient has a diastolic murmur (classically graded on a scale of 1 to 4, unlike systolic murmurs) consistent with valvular aortic regurgitation. (In contrast to the murmur of aortic regurgitation due to root dilation, best heard at the traditional aortic auscultation area in the right sternal border, the murmur of valvular aortic regurgitation is best heard at the left sternal border.) Given his history of a mechanical prosthetic aortic valve, this presentation should raise suspicion for prosthetic valve dysfunction (PVD), which most commonly occurs in the following forms:
Paravalvular leak (regurgitation around the valve): more commonly occurs with mechanical (rather than bioprosthetic) valves and results from dehiscence of the valve from the aortic or mitral annulus, often due to annular degeneration or underlying infective endocarditis.
Transvalvular regurgitation (regurgitation through the valve): more commonly affects bioprosthetic (rather than mechanical) valves and can result from cusp degeneration or occasionally valvular thrombus that impairs valve closure. Patients are often initially asymptomatic but can develop severe heart failure; those with significant regurgitation generally have a poor prognosis.
PVD can also involve valvular obstruction (stenosis), which typically results from valvular thrombus or cusp malfunction (ie, failed opening) and presents with a characteristic stenotic, rather than a regurgitant, murmur.
The best initial evaluation for PVD is echocardiography, which allows visualization of the valve and surrounding anatomy. Depending on the cause and extent of dysfunction, further studies and possible surgical intervention may be indicated.
(Choice A) PVD can cause mechanical damage to red blood cells (as they are passing through the malfunctioning valve) and lead to macroangiopathic hemolytic anemia. Complete blood count and peripheral blood smear (revealing schistocytes) are used for diagnosis. However, significant anemia is unlikely in this asymptomatic patient; in addition, mild hemolysis may be seen normally with a prosthetic valve, also making a peripheral smear less helpful.
(Choice C) Exercise stress testing is indicated for patients with symptoms consistent with stable angina (eg, chest pain reproducible with exertion and relieved by rest); however, it has limited use in evaluating this asymptomatic patient with a murmur suggesting PVD.
(Choice D) Hypercoagulability studies may be appropriate if valvular thrombus is identified. However, this patient's therapeutic INR (eg, INR 2-3 for mechanical aortic valve) and adherence to warfarin therapy make thrombus less likely. In addition, echocardiography is needed first to evaluate PVD.
(Choice E) Routine clinical follow-up is not appropriate because this patient's murmur suggests possible serious PVD that should be evaluated with echocardiography.
Educational objective:
A regurgitant murmur over a prosthetic valve suggests prosthetic valve dysfunction (PVD) in the form of a paravalvular leak or transvalvular regurgitation. PVD can lead to serious complications (eg, heart failure) and should be promptly evaluated with echocardiography.